Sulphuric acid ester of the leuco compound of a vat dyestuff



7 iratemedloi." 13; 1931 i 'WILHELM Brenna Aim LUDWIG zen, or WIESDOR-F,GEBMANYQASSIGNORS r G N; ERAL ANILINE worms, me, or new YORK, v. Y., ACORPORATION OF DELAWARE c s LPHURIc ACID ESTER or THE LEUCO COMPOUND 01?A ,yA'r' nYEsr rr No Drawing. Application filed July 3, 1930',Seria1NO.'465, 753, and in Germany July 29, 1939.; i v

I The present, invention relates to a water 7 soluble sulphuric'acidester of the leucocompound of avat dyestufi, more particularly itrelates'to the sulphuric acid ester of the r, leuco compound of 46-dichloro-6-methoxybis-thionaphthene-indigo, which in its free statehas the probable formula The British Patent No. 186,057 describes aprocess for the manufacture of stable,,water soluble sulphuric acidesters of leucocom pounds of vat dyestufis; The process con sists incausing the leuco compounds to react in the presence of a tertiaryhasewith sulphuric acid anhydrideor with agents yielding sulphuric acidanhydride, such as chlorosulfonic acid, chlorosulfonic acid methylesterand the like. V I g l In accordance with the presentinvention theparticularl' aluable ester of the above formula is obtained by applyingthe said procv ess to the leuco compound of 4: 6-tdichloro-6-methoxy-bis-thionaphthene-indigo.. The ester'thus produced'in a verysatisfactory yield is, in the form of its alkali metal salts, a stablecrystalline substance, easily soluble in water.

These salts are distinguished by the fact that, t

1 when printed or dyed on textile fibers and developed with acidoxidizing agents, they yield very clear, scarlet shades of a strengthand-fastness, which have nothitherto-been Obtainable'with sulphuric acidestersfof vat dyestuffs. f i The following example will furtherillustrate the invention EwampZe.-'6O parts by weight ofchlorosulfonicacid are introduced with cooling into a mixture of 160 parts by weightof dimethyL- aniline and 160'- parts by weight of chlorobenzene and,after-displacing the air by carbon dioxide, parts by weight of dry leuco4 6-dichloro-'6-methoxybis -thionaphtheneindigo are added. Thetemperature is raised to C. in the course'of 2h0urs while stir- 50, ringand maintained at this point for one hour.v The reaction mixture is thenpoured V into an excess of sodiumvcarbonate solution, 1 T I thedimethylaniline and chlorobenzene are only slightlycolored solution issalted out with a little sodium chloride. I

The sodium salt of the ester separates on- V y f cooling in the form ofa-whiteprecipitate oonsisting of small crystals. c soluble in water, Onacidifying with a min- It is readily eral acid and adding amild'oxidizing agent,

' the solution immediately deposits a scarlet 'red precipitate. Theester, when printed or dyed in an appropriate manner on vegetable oranimal fibers and developed wi'th'oxidizingf agents, yields deep scarletred shades of very good clarity and fastnes s. c

The. naphthene-indigo can be obtained-by 'condensingj a 2-anil of2":3-diketo-dihydro 6-v methoxy-thionaphthene with 4: 6-dichloro-3-hydroxythionaphthene or a Q-anil of 416- dichloro 3hydroxythionaphthene with ,6-

methoxy-3 hydroxythionaphthene;

The 4: 6-dichloro-3-hydrox hiona hthene v driven off by means of steamand-thefiltered, v1 7 4; 6-dichloro 6einethoxy bis-thiocan easil beobtained, for example, y causing the c loride of ,3:5-dichlorophenyl-1-thioglycolic acid toreact with aluminium' chlor1de.",I

We claim: c As a new product of the leuco compound of 4: 6-dichloro-6-fl methoxy-bis-thionaphthene-indigo, having 7 in its free form thefollowing formula I the sulphuric acid ester salt a stable, whitecrystalline substance,

readily soluble in water, yielding, when printed ondyed on textilefibers, and developed with acid oxidizing agents, very clear scarletshades of good fastnessproperties.

' In testimony tures. v

' WILHELM" BAUER.

LUDWIG -ZEH,

whereof, We afl'ix our signa- I

